U.S. patent application number 14/084034 was filed with the patent office on 2014-03-13 for delivery catheter systems and methods.
This patent application is currently assigned to Nanostim, Inc.. The applicant listed for this patent is Nanostim, Inc.. Invention is credited to Alexander Khairkhahan, Alan Klenk.
Application Number | 20140074114 14/084034 |
Document ID | / |
Family ID | 46245071 |
Filed Date | 2014-03-13 |
United States Patent
Application |
20140074114 |
Kind Code |
A1 |
Khairkhahan; Alexander ; et
al. |
March 13, 2014 |
DELIVERY CATHETER SYSTEMS AND METHODS
Abstract
A delivery system for implanting a leadless cardiac pacemaker
into a patient is provided. The cardiac pacemaker can include a
docking or delivery feature having a through-hole disposed on or
near a proximal end of the pacemaker for attachment to the delivery
system. In some embodiments, the delivery catheter can include
first and second tethers configured to engage the delivery feature
of the pacemaker. The tethers, when partially aligned, can have a
cross-sectional diameter larger than the through-hole of the
delivery feature, and when un-aligned, can have a cross-sectional
diameter smaller than the through-hole of the delivery feature.
Methods of delivering the leadless cardiac pacemaker with the
delivery system are also provided.
Inventors: |
Khairkhahan; Alexander;
(Palo Alto, CA) ; Klenk; Alan; (San Jose,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nanostim, Inc. |
Sunnyvale |
CA |
US |
|
|
Assignee: |
Nanostim, Inc.
Sunnyvale
CA
|
Family ID: |
46245071 |
Appl. No.: |
14/084034 |
Filed: |
November 19, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13324781 |
Dec 13, 2011 |
8615310 |
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14084034 |
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Current U.S.
Class: |
606/129 |
Current CPC
Class: |
A61N 1/362 20130101;
A61N 2001/058 20130101; A61N 1/3756 20130101; A61N 1/0573 20130101;
A61M 25/0074 20130101; A61N 1/057 20130101 |
Class at
Publication: |
606/129 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Claims
1. A delivery catheter for implanting a medical device, comprising:
a handle; a catheter shaft coupled to the handle; a first tether
disposed within the catheter shaft and extending distally beyond
the catheter shaft, the first tether including a first locking
feature positioned near a distal portion of the first tether; a
second tether disposed within the catheter shaft and extending
distally beyond the catheter shaft, the second tether including a
second locking feature positioned near a distal portion of the
second tether; a tether adjustment feature coupled to the first
tether, the tether adjustment feature configured to adjust a length
of the first tether extending distally beyond the catheter
shaft.
2. The delivery catheter of claim 1 wherein the delivery catheter
comprises an aligned configuration where the first and second
locking features are positioned at least partially side by side,
and an un-aligned configuration where the first and second locking
features are not positioned side by side.
3. The delivery catheter of claim 2 wherein the tether adjustment
feature facilitates switching the delivery catheter between the
aligned configuration and the un-aligned configuration.
4. The delivery catheter of claim 1 further comprising: a docking
cap disposed on a distal portion of the catheter shaft; and a
torque shaft disposed within the catheter shaft, the torque shaft
coupled to the docking cap, the torque shaft being configured to
apply rotational torque to the docking cap to rotate the docking
cap.
5. The delivery catheter of claim 1 further comprising a protective
sheath disposed on the catheter shaft, the protective sheath being
slidable along the catheter shaft and comprising a crease that runs
longitudinally along the protective sheath, wherein the protective
sheath is configured to be folded over itself along the crease to
reduce a delivery diameter of the protective sheath.
6. A method of delivering a medical device to a patient with a
delivery catheter, comprising: positioning an attachment feature of
the medical device in proximity to an attachment mechanism of the
delivery catheter; inserting the attachment mechanism of the
delivery catheter distally through a hole in the attachment feature
of the medical device, the attachment mechanism having a
cross-sectional diameter smaller than a diameter of the hole;
increasing the cross-sectional diameter of the attachment mechanism
to prevent the attachment mechanism from moving proximally back
through the hole of the attachment feature of the medical
device.
7. The method of claim 6 wherein the attachment feature comprises a
pair of tethers disposed within and extending distally beyond the
delivery catheter, each of the tethers having a locking
feature.
8. The method of claim 7 wherein the attachment feature has a
cross-sectional diameter smaller than the diameter of the hole when
portions of the locking features of the tethers are not
longitudinally aligned.
9. The method of claim 7 wherein the increasing the cross-sectional
diameter step comprises longitudinally aligning at least a portion
of the locking features of the tethers.
10. The method of claim 6 wherein the medical device comprises a
leadless cardiac pacemaker.
11. The method of claim 6 further comprising pulling the medical
device proximally with the attachment mechanism to place the
medical device in contact with a distal end of the delivery
catheter.
12. The method of claim 11 further comprising inserting the medical
device and the delivery catheter into the patient adjacent to an
implantation site, and applying rotational torque from the delivery
catheter to the medical device to screw a fixation device of the
medical device into the implantation site.
13. A method of delivering a leadless pacemaker to a patient with a
delivery catheter, comprising: positioning a first locking feature
of a first tether of the deliver/catheter at a longitudinal
position different than that of a second locking feature of a
second tether of the delivery catheter, so that a combined
cross-sectional diameter of the locking features is less than a
cross-sectional diameter of a hole in an attachment feature of the
leadless pacemaker; inserting the first and second locking features
through the hole in the attachment feature of the leadless
pacemaker; and aligning a portion of the first locking feature at
the same longitudinal position than that of a portion of the second
locking feature, so that the combined cross-sectional diameter of
the locking features and tethers is greater than the
cross-sectional diameter of the hole in the attachment feature of
the leadless pacemaker.
14. The method of claim 12 further comprising pulling the medical
device proximally with the first and second tethers to place the
leadless pacemaker in contact with a distal end of the delivery
catheter.
15. The method of claim 13 further comprising inserting the medical
device and the delivery catheter into the patient adjacent to an
implantation site, and applying rotational torque from the delivery
catheter to the leadless pacemaker to screw a fixation device of
the pacemaker into the implantation site.
Description
PRIORITY CLAIM
[0001] This application is a Divisional application of U.S. patent
application Ser. No. 13/324,781 (Attorney Docket No.
10494-708.200), filed Dec. 13, 2011, entitled "Delivery Catheter
Systems and Methods" which claims the benefit of U.S. Provisional
Patent Application No. 61/422,620, filed Dec. 13, 2010, titled
"Delivery Catheter Systems and Methods." Each patent application
identified above is incorporated herein by reference in its
entirety to provide continuity of disclosure.
INCORPORATION BY REFERENCE
[0002] All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference.
FIELD
[0003] The present disclosure relates to leadless cardiac
pacemakers, and more particularly, to features and methods by which
they are affixed within the heart. More specifically, the present
disclosure relates to features and methods for delivering a
leadless cardiac pacemaker to tissue.
BACKGROUND
[0004] Cardiac pacing by an artificial pacemaker provides an
electrical stimulation of the heart when its own natural pacemaker
and/or conduction system fails to provide synchronized atrial and
ventricular contractions at rates and intervals sufficient for a
patient's health. Such antibradycardial pacing provides relief from
symptoms and even life support for hundreds of thousands of
patients. Cardiac pacing may also provide electrical overdrive
stimulation to suppress or convert tachyarrhythmias, again
supplying relief from symptoms and preventing or terminating
arrhythmias that could lead to sudden cardiac death.
[0005] Cardiac pacing by currently available or conventional
pacemakers is usually performed by a pulse generator implanted
subcutaneously or sub-muscularly in or near a patient's pectoral
region. Pulse generator parameters are usually interrogated and
modified by a programming device outside the body, via a
loosely-coupled transformer with one inductance within the body and
another outside, or via electromagnetic radiation with one antenna
within the body and another outside. The generator usually connects
to the proximal end of one or more implanted leads, the distal end
of which contains one or more electrodes for positioning adjacent
to the inside or outside wall of a cardiac chamber. The leads have
an insulated electrical conductor or conductors for connecting the
pulse generator to electrodes in the heart. Such electrode leads
typically have lengths of 50 to 70 centimeters.
[0006] Although more than one hundred thousand conventional cardiac
pacing systems are implanted annually, various well-known
difficulties exist, of which a few will be cited. For example, a
pulse generator, when located subcutaneously, presents a bulge in
the skin that patients can find unsightly, unpleasant, or
irritating, and which patients can subconsciously or obsessively
manipulate or "twiddle". Even without persistent manipulation,
subcutaneous pulse generators can exhibit erosion, extrusion,
infection, and disconnection, insulation damage, or conductor
breakage at the wire leads. Although sub-muscular or abdominal
placement can address some concerns, such placement involves a more
difficult surgical procedure for implantation and adjustment, which
can prolong patient recovery.
[0007] A conventional pulse generator, whether pectoral or
abdominal, has an interface for connection to and disconnection
from the electrode leads that carry signals to and from the heart.
Usually at least one male connector molding has at least one
terminal pin at the proximal end of the electrode lead. The male
connector mates with a corresponding female connector molding and
terminal block within the connector molding at the pulse generator.
Usually a setscrew is threaded in at least one terminal block per
electrode lead to secure the connection electrically and
mechanically. One or more O-rings usually are also supplied to help
maintain electrical isolation between the connector moldings. A
setscrew cap or slotted cover is typically included to provide
electrical insulation of the setscrew. This briefly described
complex connection between connectors and leads provides multiple
opportunities for malfunction.
[0008] Other problematic aspects of conventional pacemakers relate
to the separately implanted pulse generator and the pacing leads.
By way of another example, the pacing leads, in particular, can
become a site of infection and morbidity. Many of the issues
associated with conventional pacemakers are resolved by the
development of a self-contained and self-sustainable pacemaker, or
so-called leadless pacemaker, as described in the related
applications cited above.
[0009] Self-contained or leadless pacemakers or other
biostimulators are typically fixed to an intracardial implant site
by an actively engaging mechanism such as a screw or helical member
that screws into the myocardium.
SUMMARY OF THE DISCLOSURE
[0010] In one embodiment, a delivery catheter for implanting a
medical device is provided, comprising a handle, a catheter shaft
coupled to the handle, a first tether disposed within the catheter
shaft and extending distally beyond the catheter shaft, the first
tether including a first locking feature positioned near a distal
portion of the first tether, a second tether disposed within the
catheter shaft and extending distally beyond the catheter shaft,
the second tether including a second locking feature positioned
near a distal portion of the second tether, a tether adjustment
feature coupled to the first tether, the tether adjustment feature
configured to adjust a length of the first tether extending
distally beyond the catheter shaft.
[0011] In some embodiments, the delivery catheter comprises an
aligned configuration where the first and second locking features
are positioned at least partially side by side, and an un-aligned
configuration where the first and second locking features are not
positioned side by side.
[0012] In some embodiments, the tether adjustment feature
facilitates switching the delivery catheter between the aligned
configuration and the un-aligned configuration.
[0013] In one embodiment, the delivery catheter further comprises a
docking cap disposed on a distal portion of the catheter shaft, and
a torque shaft disposed within the catheter shaft, the torque shaft
coupled to the docking cap, the torque shaft being configured to
apply rotational torque to the docking cap to rotate the docking
cap.
[0014] In another embodiment, the delivery catheter further
comprises a protective sheath disposed on the catheter shaft, the
protective sheath being slidable along the catheter shaft and
comprising a crease that runs longitudinally along the protective
sheath, wherein the protective sheath is configured to be folded
over itself along the crease to reduce a delivery diameter of the
protective sheath.
[0015] A leadless pacemaker and delivery system is also provided,
comprising a leadless cardiac pacemaker comprising an attachment
feature disposed on a proximal portion of the pacemaker, the
attachment feature including a through-hole having a first
diameter, and a delivery catheter comprising: a handle, a catheter
shaft coupled to the handle, a first tether disposed within the
catheter shaft and extending distally beyond the catheter shaft,
the first tether including a first locking feature positioned near
a distal portion of the first tether, a second tether disposed
within the catheter shaft and extending distally beyond the
catheter shaft, the second tether including a second locking
feature positioned near a distal portion of the second tether; and
a tether adjustment feature coupled to the first tether, the tether
adjustment feature configured to adjust a position of the first
locking feature with respect to the second locking feature, the
delivery catheter comprising an aligned configuration where a
portion of the first locking feature is longitudinally aligned with
a portion the second locking feature and comprises a combined
cross-sectional diameter larger than the first diameter of the
through-hole, the delivery catheter also comprising an un-aligned
configuration where the first locking feature is not longitudinally
aligned with the second locking feature and comprises a combined
cross-sectional diameter smaller than the first diameter of the
through-hole.
[0016] In some embodiments, the tether adjustment feature
facilitates switching the delivery catheter between the aligned
configuration and the un-aligned configuration.
[0017] In another embodiment, the catheter can further comprise a
docking cap disposed on a distal portion of the catheter shaft, and
a torque shaft disposed within the catheter shaft, the torque shaft
coupled to the docking cap, the torque shaft being configured to
apply rotational torque to the docking cap to rotate the docking
cap.
[0018] In one embodiment, the delivery catheter can further
comprise a protective sheath disposed on the catheter shaft, the
protective sheath being slidable along the catheter shaft and
comprising a crease that runs longitudinally along the protective
sheath, wherein the protective sheath is configured to be folded
over itself along the crease to reduce a delivery diameter of the
protective sheath.
[0019] A method of delivering a medical device to a patient with a
delivery catheter is also provided, comprising positioning an
attachment feature of the medical device in proximity to an
attachment mechanism of the delivery catheter, inserting the
attachment mechanism of the delivery catheter distally through a
hole in the attachment feature of the medical device, the
attachment mechanism having a cross-sectional diameter smaller than
a diameter of the hole, increasing the cross-sectional diameter of
the attachment mechanism to prevent the attachment mechanism from
moving proximally back through the hole of the attachment feature
of the medical device.
[0020] In some embodiments, the attachment feature comprises a pair
of tethers disposed within and extending distally beyond the
delivery catheter, each of the tethers having a locking
feature.
[0021] In one embodiment, the attachment feature has a
cross-sectional diameter smaller than the diameter of the hole when
portions of the locking features of the tethers are not
longitudinally aligned.
[0022] In another embodiment, the increasing the cross-sectional
diameter step comprises longitudinally aligning at least a portion
of the locking features of the tethers.
[0023] In some embodiments, the medical device comprises a leadless
cardiac pacemaker.
[0024] In one embodiment, the method comprises pulling the medical
device proximally with the attachment mechanism to place the
medical device in contact with a distal end of the delivery
catheter.
[0025] In another embodiment, the method further comprises
inserting the medical device and the delivery catheter into the
patient adjacent to an implantation site, and applying rotational
torque from the delivery catheter to the medical device to screw a
fixation device of the medical device into the implantation
site.
[0026] Another method of delivering a leadless pacemaker to a
patient with a delivery catheter is provided, comprising
positioning a first locking feature of a first tether of the
delivery catheter at a longitudinal position different than that of
a second locking feature of a second tether of the delivery
catheter, so that a combined cross-sectional diameter of the
locking features is less than a cross-sectional diameter of a hole
in an attachment feature of the leadless pacemaker, inserting the
first and second locking features through the hole in the
attachment feature of the leadless pacemaker, and aligning a
portion of the first locking feature at the same longitudinal
position than that of a portion of the second locking feature, so
that the combined cross-sectional diameter of the locking features
and tethers is greater than the cross-sectional diameter of the
hole in the attachment feature of the leadless pacemaker.
[0027] In some embodiments, the method further comprises pulling
the medical device proximally with the first and second tethers to
place the leadless pacemaker in contact with a distal end of the
delivery catheter.
[0028] In another embodiment, the method further comprises
inserting the medical device and the delivery catheter into the
patient adjacent to an implantation site, and applying rotational
torque from the delivery catheter to the leadless pacemaker to
screw a fixation device of the pacemaker into the implantation
site.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The novel features of the invention are set forth with
particularity in the claims that follow. A better understanding of
the features and advantages of the present invention will be
obtained by reference to the following detailed description that
sets forth illustrative embodiments, in which the principles of the
invention are utilized, and the accompanying drawings of which:
[0030] FIG. 1 is one embodiment of a delivery system for delivering
a leadless pacemaker.
[0031] FIGS. 2A-2B are close-up views of a distal portion of the
delivery system.
[0032] FIGS. 3A-3B are schematic side and cross-sectional views of
a pacemaker sheath.
[0033] FIGS. 4A-4G are side views of a delivery system attached to
a pacemaker.
[0034] FIGS. 5A-5D are various views of a catheter handle and
tether key.
[0035] FIGS. 6A-6B are an alternate embodiment of a delivery system
having a single tether.
DETAILED DESCRIPTION
[0036] Various embodiments for delivering system comprising one or
more leadless cardiac pacemakers or biostimulators are described. A
leadless cardiac pacemaker can communicate by conducted
communication, representing a substantial departure from
conventional pacing systems. For example, an illustrative cardiac
pacing system can perform cardiac pacing that has many of the
advantages of conventional cardiac pacemakers while extending
performance, functionality, and operating characteristics with one
or more of several improvements.
[0037] In some embodiments of a cardiac pacing system, cardiac
pacing is provided without a pulse generator located in the
pectoral region or abdomen, without an electrode-lead separate from
the pulse generator, without a communication coil or antenna, and
without an additional requirement on battery power for transmitted
communication.
[0038] An embodiment of a cardiac pacing system configured to
attain these characteristics comprises a leadless cardiac pacemaker
that is substantially enclosed in a hermetic housing suitable for
placement on or attachment to the inside or outside of a cardiac
chamber. The pacemaker can have two or more electrodes located
within, on, or near the housing, for delivering pacing pulses to
muscle of the cardiac chamber and optionally for sensing electrical
activity from the muscle, and for bidirectional communication with
at least one other device within or outside the body. The housing
can contain a primary battery to provide power for pacing, sensing,
and communication, for example bidirectional communication. The
housing can optionally contain circuits for sensing cardiac
activity from the electrodes. The housing contains circuits for
receiving information from at least one other device via the
electrodes and contains circuits for generating pacing pulses for
delivery via the electrodes. The housing can optionally contain
circuits for transmitting information to at least one other device
via the electrodes and can optionally contain circuits for
monitoring device health. The housing contains circuits for
controlling these operations in a predetermined manner.
[0039] In some embodiments, a cardiac pacemaker can be adapted for
delivery and implantation into tissue in the human body. In a
particular embodiment, a leadless cardiac pacemaker can be adapted
for implantation adjacent to heart tissue on the inside or outside
wall of a cardiac chamber, using two or more electrodes located on
or within the housing of the pacemaker, for pacing the cardiac
chamber upon receiving a triggering signal from at least one other
device within the body.
[0040] Self-contained or leadless pacemakers or other
biostimulators are typically fixed to an intracardial implant site
by an actively engaging mechanism or primary fixation mechanism
such as a screw or helical member that screws into the myocardium.
Examples of such leadless biostimulators are described in the
following publications, the disclosures of which are incorporated
by reference: (1) U.S. application Ser. No. 11/549,599, filed on
Oct. 13, 2006, entitled "Leadless Cardiac Pacemaker System for
Usage in Combination with an Implantable
Cardioverter-Defibrillator", and published as US2007/0088394A1 on
Apr. 19, 2007; (2) U.S. application Ser. No. 11/549,581 filed on
Oct. 13, 2006, entitled "Leadless Cardiac Pacemaker", and published
as US2007/0088396A1 on Apr. 19, 2007; (3) U.S. application Ser. No.
11/549,591, filed on Oct. 13, 2006, entitled "Leadless Cardiac
Pacemaker System with Conductive Communication" and published as
US2007/0088397A1 on Apr. 19, 2007; (4) U.S. application Ser. No.
11/549,596 filed on Oct. 13, 2006, entitled "Leadless Cardiac
Pacemaker Triggered by Conductive Communication" and published as
US2007/0088398A1 on Apr. 19, 2007; (5) U.S. application Ser. No.
11/549,603 filed on Oct. 13, 2006, entitled "Rate Responsive
Leadless Cardiac Pacemaker" and published as US2007/0088400A1 on
Apr. 19, 2007; (6) U.S. application Ser. No. 11/549,605 filed on
Oct. 13, 2006, entitled "Programmer for Biostimulator System" and
published as US2007/0088405A1 on Apr. 19, 2007; (7) U.S.
application Ser. No. 11/549,574, filed on Oct. 13, 2006, entitled
"Delivery System for Implantable Biostimulator" and published as
US2007/0088418A1 on Apr. 19, 2007; and (8) International
Application No. PCT/US2006/040564, filed on Oct. 13, 2006, entitled
"Leadless Cardiac Pacemaker and System" and published as
WO07047681A2 on Apr. 26, 2007.
[0041] In addition to the primary fixation mechanism, such as a
helix, some biostimulators may further include a secondary fixation
mechanism to provide another feature for keeping the biostimulator
in place within the body. Secondary fixation mechanisms can be
either active (e.g., the secondary fixation mechanism can actively
engage tissue, either within or outside the heart), or can be
passive (e.g., the secondary fixation mechanism is not attached to
tissue but rather prevents the biostimulator from moving around in
the body in the case of accidental detachment). Further details on
secondary fixation mechanisms can be found in U.S. application Ser.
No. 12/698,969.
[0042] Leadless pacemakers or biostimulators can be delivered to
and retrieved from a patient using any of the delivery systems
described herein. In some embodiments, a biostimulator is attached
or connected to a delivery system and advanced intravenously into
the heart. The delivery system can include features to engage the
biostimulator to allow fixation of the biostimulator to tissue. For
example, in embodiments where the biostimulator includes an active
engaging mechanism, such as a screw or helical member, the delivery
system can include a docking cap or key configured to engage the
biostimulator and apply torque to screw the active engaging
mechanism into the tissue. In other embodiments, the delivery
system includes clips designed to match the shape of a feature on
the biostimulator and apply torque to screw the active engaging
mechanism into the tissue.
[0043] FIG. 1 illustrates a pacemaker delivery system 100
configured for delivery of a leadless pacemaker 102 into a patient.
The delivery system 100 can include pacemaker sheath 104, guide
catheter shaft 111, pacemaker introducer sheath 107, handle 108,
deflection knob 110, tether shuttle 112, and flush ports 114a,
114b, and 114c The deflection knob 110 can be used to steer and
guide the catheter during implantation and/or removal of the
pacemaker. The flush ports 114a, 114b, and 114c can be used to
flush saline or other fluids through the catheter. Sheath 107 can
be advanced distally over catheter shaft 111 to provide additional
steering and support for the delivery catheter during implantation
and to surround the pacemaker as it is introduced through a trocar
or introducer into the patient.
[0044] FIG. 2A is a close-up view of a distal portion of delivery
system 200 and pacemaker 202. The pacemaker of FIG. 2A can include
a helix 203 for attachment of the pacemaker to tissue. In FIG. 2A,
the pacemaker is attached to docking cap 218 of catheter shaft 206.
Pacemaker sheath 204 is shown pulled back proximally along catheter
shaft 206 and guide catheter shaft 211 to expose the pacemaker 202
and helix 203. In FIG. 2B, pacemaker sheath 204 is extended
distally along guide catheter shaft 211 to cover the catheter shaft
206, pacemaker 202, and helix to protect the tissue from the sharp
edges of the helix during implantation. When the pacemaker sheath
is pulled back proximally, as shown in FIG. 2A, the pacemaker 202
is in an exposed, delivery configuration. When the pacemaker sheath
is advanced distally to protect the pacemaker and helix, as shown
in FIG. 2B, the pacemaker 202 is in a protected, advancement
configuration.
[0045] FIGS. 3A-3B are close-up and cross sectional views of
pacemaker sheath 304 of delivery system 300. As shown, pacemaker
sheath 304 can include crease or fold 320 along the length of the
sheath. During initial insertion of the delivery system into a
patient, a physician can gain access to the patient's venous system
with an introducer sheath using the Seldinger technique (not
shown). The delivery system, including the leadless pacemaker and
catheter shaft, can then be advanced through the introducer sheath
into the patient's venous system to facilitate delivery of the
pacemaker into the heart. Reducing the diameter of the pacemaker,
the delivery system, and thus the introducer sheath, provides for
easier and less intrusive access to a patient's venous system.
[0046] By designing pacemaker sheath 304 with a fold 320 that runs
longitudinally along the sheath, the cross sectional diameter of
the pacemaker sheath can be reduced by folding the sheath over
itself. Thus, during initial implantation of the pacemaker through
a introducer sheath into the patient, the pacemaker sheath can be
positioned just proximally to the pacemaker, and folded along fold
320 so as to have a cross sectional diameter close to or equal to
the same diameter as the pacemaker. This allows a smaller diameter
introducer sheath to be used than would normally be necessary,
since those delivery systems must incorporate a larger introducer
sheath to allow passage of a full sized pacemaker sheath. After the
delivery system is inserted through the introducer sheath into the
patient, the sheath can be advanced distally over the leadless
pacemaker. Advancing the pacemaker sheath distally causes fold 320
to unfold, thereby increasing the diameter of the pacemaker sheath
so that it can slide over and cover the pacemaker and fixation
helix. FIG. 3B is a cross sectional view of the pacemaker helix 304
and fold 320, giving another view on how the cross sectional
diameter of the pacemaker sheath can increase and decrease.
[0047] FIG. 4A illustrates delivery system 400, including pacemaker
402 comprising helix 403 and attachment feature 424, and the
delivery catheter comprising pacemaker sheath 404, catheter shaft
406, docking cap 418, and tethers 422a and 422b. The tethers can
comprise wires, shafts, tubes, cords, ropes, strings, or other
similar structures that can extend throughout the catheter shaft.
In some embodiments, the tethers comprise a shape memory material,
such as nitinol. In other embodiments, the tethers comprise
stainless steel wires or braids. In FIG. 4A, the pacemaker 402 is
not attached to docking cap 418 of the delivery catheter. The
process of connecting the pacemaker to the delivery catheter will
now be described.
[0048] Referring to FIG. 4B, tethers 422a and 422b can include
distal features 426a and 426b. The distal features can be, for
example, features on the tethers that protrude radially from the
tether, such as bumps, spheres, cylinders, rectangles, or other
similar shapes extending outwards from the tethers. In some
embodiments, the distal features can be expandable, such as
balloons or expandable mechanical structures. Generally, the distal
features have a cross sectional diameter larger than the cross
sectional diameter of the tethers. As shown, in one embodiment,
distal feature 422a can be advanced further from the catheter than
distal feature 422b, so that when the tethers are pushed together,
distal feature 422b rests against tether 422a. This causes the
combined cross sectional diameter of both distal features and
tethers to be less than if the distal features were lined up side
by side. By way of comparison, in FIG. 4C the distal features 426a
and 426b are lined up side by side and therefore have a greater
combined cross sectional diameter when pressed together than is
shown in FIG. 4B.
[0049] To connect the delivery catheter to the pacemaker, the
length of tethers 422a and 422b, and thus the position of distal
features 426a and 426b, can be adjusted so that distal features
426a and 426b are not aligned in a side by side configuration
(e.g., the un-aligned configuration shown in FIGS. 4A-4B). When the
tethers and distal features are in this un-aligned configuration,
the cross sectional diameter of the distal features is reduced
since the distal features are not positioned side by side. The
tether distal features 426a and 426b can then be advanced in this
un-aligned configuration through hole 428 of attachment feature
424, as shown in FIGS. 4D-4F. In this embodiment, the diameter of
hole 428 should be sufficiently large enough to allow the distal
features 426a and 426b of tethers 422a and 422b to pass when in the
un-aligned configuration. Upon passing the distal features through
the hole 428, the length of the tethers can then be adjusted to
align the distal features in the side by side configuration (e.g.,
as shown in FIGS. 4C and 4E). When the distal features are
positioned side by side, the combined cross sectional diameter of
the distal features becomes larger than the diameter of hole 428,
which essentially locks the tethers and distal features in the
attachment feature 424 be preventing the distal features from being
able to pass proximally through the hole 428.
[0050] Still referring to FIGS. 4C and 4D, the docking cap 418 of
the delivery catheter can include a torque slot 430 (shown in FIG.
4C) sized and configured to mate with a torque key 432 (shown in
FIG. 4D) disposed on a proximal end of the pacemaker. The torque
slot 430 can be coupled to a torque shaft 431, which runs the
length of the delivery catheter extending into the handle (not
shown). In FIGS. 4C and 4D, torque key 430 is shown as a "male" key
and torque slot 430 is shown as a "female" key, but it should be
understood that in other embodiments, the "male" key can be located
on the attachment feature 418, and the "female" key can be disposed
on the pacemaker. It should also be appreciated that key 432 and
slot 430 can comprise any number of shapes, such as square,
rectangle, triangle, pentagon, hexagon, cross, "X", etc, so long as
key 432 fits within and can apply rotational torque to slot 430.
Once the tethers are locked within the attachment feature, the
tethers can be pulled proximally to pull attachment feature 424 and
the pacemaker towards the catheter and to attach the pacemaker to
the delivery catheter, thereby engaging torque slot 430 with torque
key 432 (as shown in FIG. 4G).
[0051] FIGS. 5A-5D are close-up views of handle 508 of delivery
system 500. In FIG. 5A, handle 508 includes deflection knob 510,
tether knob 512, tether adjustment feature 514, and flush ports
516. As described above, deflection knob 510 provides for steering
and guidance of the catheter during implantation and/or removal of
the pacemaker. The flush ports 516 can be used to flush saline or
other fluids through the catheter. Referring now to FIGS. 5B and
5C, tether adjustment feature 514 can be configured to adjust then
length of tethers 522a and 522b that extends distally outwards from
the delivery catheter, causing the distal features (not shown) to
be in either a side by side "locked" configuration or an un-aligned
"unlocked" configuration.
[0052] The tether adjustment feature can comprise an Allen wrench
or any other suitable key, and can be configured to mate with and
engage proximal keys 534a and 534b of tethers 522a and 522b,
respectively, which are disposed within shuttle 512. In another
embodiment, the tether adjustment feature can comprise knobs or
dials on the handle itself, and a user can simply turn the knobs or
dials to adjust the length of the tethers. The shuttle can be
inserted into handle 508, as shown in FIG. 50. The proximal keys
534a and 534b of tethers 522a and 522b are shown without shuttle
536 in FIG. 5C for ease of illustration. Rotation of tether
adjustment feature 514 causes proximal keys 534a and/or 534b to
move distally or proximally within shuttle 512, which therefore
changes the length of tethers 522a and/or 522b extending distally
from the delivery catheter. Thus, the tether key can be used to
either align the distal features of the tethers in a side by side
(e.g., locked) configuration, or alternatively, to place the distal
features of the tethers in an un-aligned (e.g., unlocked
configuration), permitting docking and locking of the pacemaker to
the delivery catheter.
[0053] Referring back to FIGS. 4D-4G and 5A, it can now be
understood how the pacemakers described herein can be delivered and
attached to tissue, and then released from the delivery system. In
FIGS. 4D-4F, tethers 422a and 422b can be inserted in an "unlocked"
or un-aligned configuration into hole 428 of attachment feature
424. The distal features of the tethers can then be aligned so as
to lock the distal features in the attachment feature. Referring to
FIG. 5A, tether shuttle 512 can then be pulled proximally to cause
the tethers to move proximally, thereby docking the pacemaker
against the delivery catheter (as shown in FIG. 4G). When the
pacemaker is docked against the delivery catheter, torque key 432
of the pacemaker (shown in FIG. 4D) fits within and is mated to
torque slot 420 of the delivery catheter (shown in FIG. 4C).
[0054] Referring to FIG. 5A, tether shuttle 512 of handle 508 can
then be rotated, which rotates torque shaft 431 (shown in FIG. 40)
within the delivery catheter and applies torque to torque slot 430,
and thus to torque key 432 on the pacemaker. By rotating the
shuttle, and thus the torque shaft, the delivery catheter applies
torque to the pacemaker to screw the fixation helix of the
pacemaker into tissue. Once the fixation helix is fully inserted
into tissue, the tethers can be placed into an un-aligned or
"unlocked" configuration with tether adjustment feature 514,
allowing the tethers and distal features to be removed from the
attachment feature of the pacemaker. Once the delivery catheter is
disengaged from the pacemaker, the catheter can be removed from the
patient, leaving the pacemaker in place at the target tissue.
[0055] FIGS. 6A and 6B illustrate an alternate embodiment for
attaching a delivery catheter to a pacemaker. The embodiment shown
in FIGS. 6A and 6B employs a similar concept to that described
above. However, instead of using two tethers, as described above,
the embodiment of FIGS. 6A and 6B utilizes a single tether 622,
having both a distal feature 626a and a proximal feature 626b. In
the embodiment of FIGS. 6A and 6B, the tether 622 can comprise a
shape memory alloy, such as nitinol, and can include a pre-bent or
pre-biased shape. This pre-biased shape can allow the distal
feature 626a of the tether to naturally bias outwards, as shown in
FIG. 6A.
[0056] To attach the pacemaker 602 to the delivery catheter, as
shown in FIG. 6A, the distal feature 626a of tether 622 can be
threaded through attachment feature 624 of pacemaker 602. Once the
tether is threaded through the attachment feature, the tether can
be folded back against itself, so that distal feature 626a is
adjacent to, but not directly beside proximal feature 626b. The
distal and proximal features should be aligned in an un-aligned or
"unlocked" configuration, as described above in the two-tether
embodiments. This configuration allows the distal and proximal
features to be inserted into hole 628 of docking cap 618, as shown
in FIG. 6B. Once the distal and proximal features are advanced past
the hole 628, an interior chamber (not shown) in the catheter opens
up to a diameter larger than the diameter of the hole 628. This
interior chamber has a diameter large enough to accommodate both
the distal and proximal features in a side by side or "locked"
configuration. Thus, the length of the tether can be adjusted to
align the distal and proximal features in the side by side
configuration, causing the combined cross sectional diameter of the
distal and proximal features to be larger than the diameter of hole
628. The result is the locking of tether 622 within the delivery
catheter.
[0057] Other features of the embodiment of FIGS. 6A-6B can be the
same as described above, such as the torque keys, slots, and shafts
that allow the delivery catheter to apply rotational torque to the
pacemaker to screw it into tissue.
[0058] As for additional details pertinent to the present
invention, materials and manufacturing techniques may be employed
as within the level of those with skill in the relevant art. The
same may hold true with respect to method-based aspects of the
invention in terms of additional acts commonly or logically
employed. Also, it is contemplated that any optional feature of the
inventive variations described may be set forth and claimed
independently, or in combination with any one or more of the
features described herein. Likewise, reference to a singular item,
includes the possibility that there are plural of the same items
present. More specifically, as used herein and in the appended
claims, the singular forms "a," "and," "said," and "the" include
plural referents unless the context clearly dictates otherwise. It
is further noted that the claims may be drafted to exclude any
optional element. As such, this statement is intended to serve as
antecedent basis for use of such exclusive terminology as "solely,"
"only" and the like in connection with the recitation of claim
elements, or use of a "negative" limitation. Unless defined
otherwise herein, all technical and scientific terms used herein
have the same meaning as commonly understood by one of ordinary
skill in the art to which this invention belongs. The breadth of
the present invention is not to be limited by the subject
specification, but rather only by the plain meaning of the claim
terms employed.
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